A buffer overflow flaw was found in how Asterisk parsed SIP SDP headers:
The format attribute resource for h264 video performs an
unsafe read against a media attribute when parsing the SDP.
The vulnerable parameter can be received as strings of an
arbitrary length and Asterisk attempts to read them into
limited buffer spaces without applying a limit to the
number of characters read. If a message is formed
improperly, this could lead to an attacker being able to
execute arbitrary code remotely.
This affects the 11.x series of Asterisk and is corrected in version
11.2.2. Earlier versions are not affected.
External References:
http://downloads.asterisk.org/pub/security/AST-2013-001.html